The development of enzyme biocatalysts that are reusable and able to work in heterogeneous reaction systems is the focus of this proposal. A reversibly soluble polymer is to be attached to the enzymes. Consequently, the biocatalyst can be precipitated without enzyme denaturation after product separation. Later the biocatalyst can be solubilized again in a suspension of the starting materials at the initial conditions. Therefore, these biocatalysts acquire the advantages of free enzymes (high activity in heterogeneous systems) and of immobilized enzymes (the possibility of a reuse). Biocatalysis is underutilized in industry due to the industry requirement that the biocatalyst should be reusable and the reaction have a high throughput. Solubility of the compounds is limited and this necessitates running the reactions in heterogeneous suspension of the starting materials and the products. However, today all biocatalysts on the market either cannot be reused or do not work in heterogeneous systems. Potential of the idea proposed was demonstrated on model systems. The proposal focuses on the optimization of the process using the enzymes of industrial interests. This biocatalyst will be marketed to pharmaceutical companies and used to manufacture chiral pharmaceuticals. In 1999, the market for such biocatalysts is $150 - 200 million. PROPOSED COMMERCIAL APPLICATIONS: The enzyme of biocatalysts described are unique because they combine advantages of free and immobilized enzymes. There are no biocatalysts of this kind commercially available and an enormous potential exists because most drugs are developed in a single enantioselective form.